1. Field of the Invention
The present invention relates to a running wheel for traveling units which are movable on rails, especially for traveling cranes. More specifically, the present invention relates to a running wheel in which destructive torque peaks are effectively damped by a resilient hub positioned between the drive shaft and the running rim, said running rim contacting the rail on which the running wheels roll.
2. Description of the Related Art
The German Utility Model DE 83 13 096 U1 discloses a driven running wheel for a vehicle which is movable on rails, especially for a crane, which has a running ring (roller lining) and an internally-toothed wheel hub being shrunk within a central opening of the running ring. The internal toothing of the wheel hub is arranged symmetrically to a vertical center plane of the running wheel. The running wheel is supported via roller bearings on the tubular axle of the running wheel. The axle is in turn connected with a supporting structure of the running wheel so that it is fixed with respect to rotation relative to it. A drive shaft of a transmission or gear unit projects into the hub and is in a frictional engagement for transmitting torque. For this purpose, the connection between the drive shaft and the hub is effected via a plurality of cooperating toothed wheels which form a planetary gear set arranged within the hub.
A disadvantage in this prior art running wheel is that torque peaks, such as those occurring when the direction of the running wheel is changed, are directly applied to the gear unit, which results, at best, in a reduced life of the gear unit. At worst, in the event of extreme overloading, the gear unit is destroyed. A further disadvantage of this prior art running wheel is that the hub of this running wheel is complicated and therefore difficult to manufacture.
To prevent bending moments and transverse forces from being transmitted to a drive shaft, it is known, for example, from German reference DE 40 21 054 C2, to arrange a resilient element between a gear unit and a connection steel plate (housing), forward of the gear unit, in a torque converter bearing not of the generic type. For this purpose, the resilient element is constructed as an outer ring with internal toothing which is produced from plastic that is deformable under tension.
Another prior art crane running wheel is known from German reference DE-OS 2 034 107. This prior art crane running wheel is formed entirely from plastic and an internal toothing of this prior art running wheel engages the toothing of a drive shaft. Such prior art crane running wheels can only be used with relatively small carried loads, since plastic does not have the strength of steel or cast iron.